Converting my XT500 project to 12v, fitted a 12v Reg / Rec finding that I lose spark if I ground the Reg / Rec.Magneto is a simple design with 2 coils, one for ignition and other is a shared charging / lighting coil, all coils use a common engine ground.Bike is a early series with points ignition.

It would be nice for those of us that bothered to read your post to know how you fixed it and not just that you fixed it.

Any modifications you undertake are your sole responsibility, I am not liable for any claims relating to modifications or suggestions posted on this forum. If you undertake any modifications you do so at your own risk.

Yamaha use a steel band behind the coil plate to hold the wires in place. Mine had the lighting and ignition wires crossed over so with 40 years of heat and pressure the insulation flattened out enough that they started to interact with each other.Once the lighting coil is grounded out via the regulator it also grounded the ignition coil. Not a easy one to find

thanks for letting us know - old bikes sure can throw some problems and most times they are a challenge to find. I remember the xt500 well as we used to thrash the sh1t out of them and they just continued to keep going. Big single thumpers sure can be a handful in the bush but that was half the fun.I am patiently waiting for an old mate to sell me his 1943 iron head that has been in his barn for over 30 years - I imagine when I start working on that it will throw up some curly problems. I guess thats half the fun.Good job on the xt and enjoy the ride.

Any modifications you undertake are your sole responsibility, I am not liable for any claims relating to modifications or suggestions posted on this forum. If you undertake any modifications you do so at your own risk.